Renal histology 43 Flashcards
the proximal straight tubule is also called_________
thick descending portion of loop of henle
job of this is to recover whatever wasn’t absorbed at the proximal convoluted tubule
Where its he proximal straight tubule found?
medullary ray of the cortex and outer medulla
compare the cells of proximal straight tubule to Proximal convoluted tubule
shorter cells than proximal convoluted tubules with poorly developed brush border and less complex basolateral and lateral interdigitations than the PCTs
-fewer and smaller mitochondria scattered throughout the cytoplasm
Where is the thin segment of the loop of Henle found?
SLIDE 7 what is the epithelium?
- nuclei bulges into lumen
longer in the juxtamedullary nephrons and are found in the inner medulla - 4 segments based on shape, contents of organelles, depth of tight junctions, and water permeability
thin simple squamous in both ascending and descending limbs in short nerphrons
What is vasa recta in the kidney for?
countercurrent exchange=
we want to keep medulla in state of hyperosmolarity.
Functions of vasa recta as a countercurrent exchange system
SLIDE 9
- remember vasa recta has blood cells inside
-arteriole and venule rectae form loops parallel to the loop of Henle ( fenestrated capillaries)
- Help maintain osmotic gradient in the interstitium
-hypertonic interstitial
causes loss of water from the arterioles as they descend into medulla
movement of water into the venules as they ascend
where is the distal straight tubule found?
SLIDE 11
thick ascending limb; medullary ray of the cortex. found in outer medulla
shorter cells with blunted brush border and less complex basolateral and lateral interdigitations
smaller cells with less mitochondria scattered throughout the cytoplasm
what is another name for the distal straight tubule of Henle?
thick ascending limb
what is the purpose of the distal straight tubule of the loop of Henle?
SLIDE12
look at diff of straight ascending and straight descending on slide 13
this is in the cortex, it contains renal corpuscles and that’s only in the cortex, it Is found at the medullary rays.
- cortex part found in the medullary rays
- transports ions form the lumen of the tubule to the interstitium via mainly active transport
- Reabsorption of other ions Ca2+ and Mg2+
alot of sodium postassium atpase pumps near interdigitations, little mitochondria
describe the distal convoluted tubule
SLIDE 15
compare histo of slide 14 between distal convoluted tubule and proximal convoluted tubule
very short, starts at the macula dense and ends at the connecting tubule
- less numerous profile in sections as it is 1/3 the length of PCT
- simple cuboidal epithelium
smaller cells therefore more nuclei visible
less adcidophilic cytoplasm
functions of distal convoluted tubule
SLIDE 15
- fewer and shorter/blunted microvilli and extensive basal folds
- apically placed nucleus
Functions: - Reabsorption; Na+ and secretion of K+ bicarbonate and secretion of H+ - secretion of ammonium - parathyroid regulated Ca2+ reabsorption -relatively impermeable to water - highest Na/K ATPase activity.
Where is the macula densa located?
SLIDE 16/18
located at the distal straight tubule vascular pole forms part of the juxtaglomerular apparatus which regulates blood pressure.
what is the function of macula densa?
SLIDE 16
regulates blood pressure, modified cells of the distal straight tubule,
it sense changes in Na+ concentration within the lumen of the distal tubule and sends the signals to the juxtaglomerular cells ( modified smooth muscle cells) located in afferent arterioles
How does macula densa help regulate blood pressure?
osmoreceptors
How does the kidney help regulate blood pressure?
the juxtaglomerular apparatus
what are the components of the juxtaglomerular apparatus?
what are their jobs?
I= Macula densa
II= Extraglomerular mesangial cells ( Lacis and Polkissen cells) ( these are diff names for the same thing== responsible for communication between macula densa and JG cells ( juxtaglomerular cells)
III= Juxtaglomerular cells (JG)
- modified smooth muscle cells of afferent arteriole
- Produce renin that cleaves angiotensinogen to angiotensin I
what does the activation of angiotensin II stimulate?
vasoconstriction, aldosterone secretion from adrenal cortex, aldosterone stimulates reabsorption of Na, and secretion oof K+ by connecting tubules and collecting ducts.
The vasa recta and the thin loop of henle are found where?
the inner medulla
Are there thick limbs of henle in the inner medulla? SLIDe 10
nope
A tubular structure with apically located nuclei and cuboidal epithelium with blunted brush border, what tubular structure is it?
A- proximal convoluted tubule B-renal corpuscle C thin ascending D-Distal convoluted Et- think descending
Answer is D=
A has well developed brush border and also cuboidal
what occurs if there is a low blood volume entering the renal corpuscle entering the afferent arteriole?
it activates JG cells that regulate blood pressure
What occurs if we have a low sodium concentration at the distal straight tubule sensed by the macula densa what occurs?
the extraglomerular cells signal the JG cells and angiotensin is activated.
Describe the path for an increase in blood pressure with angiotensin II
this is slide 20
in the liver angiotensinogen exists and then it is changed to angiotensin 1
In the lungs angiotensin 1 turns to angiotensin 2 via the ACE enzyme
Then at the cortex of the adrenal gland angiotensin 2 turns into aldosterone.
then aldosterone causes kidney reabsorption of sodium, and secretion of K+ by connecting tubules and collecting ducts. the blood pressure increases like this
all this causes vasoconstriction as well
what is the job of the connecting tubules?
it connects the DCT to cortical collecting duct
aldosterone can affect this too because it secretes K+ into lumen
